1. Field of the Invention
The invention relates to a method of manufacturing sealing compositions for electric cables.
2. Discussion of the Background
Sealing compositions for electric cables should have the following combination of properties:
(a) One should be able to prepare the composition by simple mixing of components which can be obtained readily and at favorable cost (economy).
(b) The composition should be easily processible, i.e. it should be possible to pour the composition at ambient temperature.
(c) The composition should be characterized by a high dielectric strength (high breakdown voltage for a given electrode separation), and accordingly by a high electrical insulation value (safety).
The production of sealing compositions for electric cables by mixing PVC, inorganic fillers, and additives is known. Such compositions have properties a and b supra. However, they are deficient as to property c.
Japanese OS No. 56-109,237 discloses sealing compositions for electric cables prepared by mixing a binder component, an inorganic filler, and additives. The binder component is comprised of a liquid polybutadiene and other binding agents. With these compositions as well, the combination of properties described supra is unsatisfactory however.
Accordingly, there remains a strongly felt need both for sealing compositions for electric cables and a method of manufacturing such sealing compositions, where the compositions can be prepared by simple mixing of readily available components, are easily processed, and are also characterized by high dielectric strength and a high electrical insulation value.